http://bugs.python.org/issue2459 -- speed up loops

Lib/test/test_dis.py

Index: Lib/test/test_dis.py
===================================================================
--- Lib/test/test_dis.py	(revision 70087)
+++ Lib/test/test_dis.py	(working copy)
@@ -22,6 +22,33 @@
      _f.func_code.co_firstlineno + 2)
 
 
+def loop(a):
+    while a > 0:
+        a -= 1
+    return a
+
+dis_loop = """\
+%3d           0 SETUP_LOOP              26 (to 29)
+              3 JUMP_FORWARD            10 (to 16)
+
+%3d     >>    6 LOAD_FAST                0 (a)
+              9 LOAD_CONST               1 (1)
+             12 INPLACE_SUBTRACT
+             13 STORE_FAST               0 (a)
+
+%3d     >>   16 LOAD_FAST                0 (a)
+             19 LOAD_CONST               2 (0)
+             22 COMPARE_OP               4 (>)
+             25 POP_JUMP_IF_TRUE         6
+             28 POP_BLOCK
+
+%3d     >>   29 LOAD_FAST                0 (a)
+             32 RETURN_VALUE
+"""%(loop.func_code.co_firstlineno + 1,
+     loop.func_code.co_firstlineno + 2,
+     loop.func_code.co_firstlineno + 1,
+     loop.func_code.co_firstlineno + 3)
+
 def bug708901():
     for res in range(1,
                      10):
@@ -35,16 +62,14 @@
  %-4d         9 LOAD_CONST               2 (10)
              12 CALL_FUNCTION            2
              15 GET_ITER
-        >>   16 FOR_ITER                 6 (to 25)
-             19 STORE_FAST               0 (res)
-
- %-4d        22 JUMP_ABSOLUTE           16
-        >>   25 POP_BLOCK
+             16 JUMP_FORWARD             3 (to 22)
+        >>   19 STORE_FAST               0 (res)
+        >>   22 FOR_ITER                19
+             25 POP_BLOCK
         >>   26 LOAD_CONST               0 (None)
              29 RETURN_VALUE
 """%(bug708901.func_code.co_firstlineno + 1,
-     bug708901.func_code.co_firstlineno + 2,
-     bug708901.func_code.co_firstlineno + 3)
+     bug708901.func_code.co_firstlineno + 2)
 
 
 def bug1333982(x=[]):
@@ -59,13 +84,13 @@
               9 BUILD_LIST               0
              12 LOAD_FAST                0 (x)
              15 GET_ITER
-        >>   16 FOR_ITER                12 (to 31)
-             19 STORE_FAST               1 (s)
+             16 JUMP_FORWARD             9 (to 28)
+        >>   19 STORE_FAST               1 (s)
              22 LOAD_FAST                1 (s)
              25 LIST_APPEND              2
-             28 JUMP_ABSOLUTE           16
+        >>   28 FOR_ITER                19
 
- %-4d   >>   31 LOAD_CONST               2 (1)
+ %-4d        31 LOAD_CONST               2 (1)
              34 BINARY_ADD
              35 RAISE_VARARGS            2
 
@@ -116,6 +141,9 @@
     def test_dis(self):
         self.do_disassembly_test(_f, dis_f)
 
+    def test_lineno_goes_backwards_in_loop(self):
+        self.do_disassembly_test(loop, dis_loop)
+
     def test_bug_708901(self):
         self.do_disassembly_test(bug708901, dis_bug708901)